IRNSS Signal Plan

Fundamentals
Title	IRNSS Signal Plan
Author(s)	J.A Ávila Rodríguez, University FAF Munich, Germany.
Level	Advanced
Year of Publication	2011

In this article are described the signals corresponding to the Indian Regional Navigational Satellite System (IRNSS), which is a regional satellite navigation system owned by the Indian government. The system is being developed by Indian Space Research Organization (ISRO).

In April 2016, with the last launch of the constellation's satellite, IRNSS was renamed Navigation Indian Constellation (NAVIC) by India’s Prime Minister Narendra Modi.

The messaging service signals from the Indian Regional Navigation Satellite System (IRNSS) are broadcast in L5 and S band frequencies. The carrier frequency and the bandwidth of transmission for the messaging service are:

IRNSS Carrier Frequencies and bandwidths

Signal	Carrier Frequency	Bandwidth
L5	1176.45 MHz	24 MHz (1164.45 -1188.45 MHz)
S	2492.028MHz	16.5 MHz (2483.778 - 2500.278 MHz)

In the following figures are shown the L5 and S bands in the spectrum of Radio Navigation Satellite Services.

Figure 1: Spectrum for Radio Navigation Satellite Services in L Band.

Figure 2: Spectrum for IRNSS Signal in S Band.

Given the similarity with the Galileo signals in terms of services that IRNSS might be providing, the same convention as for Galileo was employed. That is A for the PRS and B and C for the Open Service data and pilot signals respectively. Furthermore, the spectral properties of the IRNSS signal would be as follows:

Figure 3: Spectra of IRNSS Signals in the E5b band.

To conclude, it is interesting to mention that the Indian Satellite Navigation Programme has been doing much work in the past years on ionospheric and tropospheric modelling in the Region of India what could mean that IRNSS does not plan to use dual frequency at least in the first generation.

Moreover, India also plans to transmit similar signals for the S-band to those we have just described for the L5 band. The carrier frequency of S-band is at 2491.75 MHz. The modulation schemes and data rates would be the same as for L5 but no final decision on the other parameters has been made yet. In addition, it seems that India also plans to transmit signals in L1 as announced during the second Meeting of the ICG in India, in 2007.

As a summary of the studied regional satellite systems so far, the signal plan IRNSS is shown in the next figure:

Figure 1: IRNSS planned signals.

Credits

The initial information presented in this NAVIPEDIA’s article was an extract of the PhD work performed by Dr. Jose Ángel Ávila Rodríguez in the FAF University of Munich as part of his Doctoral Thesis “On Generalized Signal Waveforms for Satellite Navigation” presented in June 2008, Munich (Germany)

This article has been updated by GMV considering the information stated in the latest IRNSS Signal Interface Specification.